The long term objective of this project is to develop a novel class of therapeutics based on Triple-Helix Forming Oligonucleotides (TFOs). In this proposal, attachment of lipophilic groups to anti-cancer and anti- HSV-2 TFOs will be examined to enhance their cellular efficacy. Specifically, cholesteryl modified TFOs that are designed to bind to the consensus progesterone response element and the lE 175 promoter of HSV-2 will be examined in detail. Preliminary data indicate that the cellular efficacy of sequence specific TFOs are increased considerably due to the attachment of cholesterol. In the Phase l study, the emphasis will be to confirm these results and undertake a systematic investigation on the mechanism of this enhancement. In addition, uptake, stability, cellular distribution, toxicity and the aggregation properties of the TFOs in aqueous solutions will be studied. The effects of attaching cholesterol through novel linkers of various lengths as well as reversible disulfide linkages will also be examined. In Phase II, using methods that are currently being developed in our laboratory for large scale synthesis, gram quantities of these modified TFOs will be synthesized. Encapsulation of the TFOs with liposomes will be performed. Cholesteryl TFOs and the encapsulated TFOs will be used for pharmacokinetic and cellular distribution studies in mice.